This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Solving the structure with a view to understanding the function of membrane proteins remains one of the grand challenges in all of Biology. Given that at least a quarter of most genomes codes for membrane proteins, many of which are targets of disease causative and treatment agents, the health consequences of meeting the challenge are great. We take a multifaceted approach to advancing our understanding of membrane protein function by producing crystals for use in macromolecular crystallography. Crystallization in lipidic mesophases by the in meso method is being used with eukaryote and prokaryote, integral and peripheral, monomeric and multimeric proteins, as well as with protein-protein and protein-peptide complexes.